Shoe bottom filling material and method of making the same



Patented July 31, 1934 PATENT OFFICE snon BOTTOM FILLING MATERIAL ANDMETHOD or MAKING THE SAME Richard .Almy, Lancaster, Pa., assignor toArmstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania vi No Drawing. Application May 5, 1932,

' Serial N0. 609,503

9 Claims.

This invention relates to shoe bottom filling material and moreparticularly to abottom filling material which can be spread into theshoe cavity in a cold condition as contrasted with bottom ,5 fillerswhich depend upon a thermoplastic binder which must be rendered workableby the application of heat or heat and moisture.

The most commonly used shoe filler of the hot or thermoplastic typeconsists of a filler such as cork particles held together with athermoplastic binder such as wax tailings. The mass is formed intoloaves at the manufactory and supplied-to the shoe trade in that shape.The material is usually broken into small pieces and placed in heatingdevices which render-the binder plastic and permit application of thefiller to the shoe cavity by means of a heated spreading tool. Uponcooling, the binder hardens and returns to its original condition.

The hot fillers have never been entirely satisfactcryfrom a productionnor a quality standpoint. The temperature of the heaters must becarefully watched or the filler will char; the mass is of a sticky,messy nature and requires careful manipulation in order to preventsmearing of the shoe upper upon handling by the filler operator. Thehotfillers due to their thermoplasticity are readily deformed and take a.permanent set when deformed by pressure. On account of the meltingnature of the binder, the material has a tendency to bunch and formridges in, the innersole around that portion which is engaged by theball of the foot. There has always been the problem of staining. Thisstaining is particu larly prevalent in womens shoes where a high grade,thin flexible outersole is used. This somewhat porous and readilyabsorbs the binder of the filler, carrying it throughout the sole :andcausing discoloration of the outer surface of the outsole. There hasalso been considerable diffi: culty encountered due to the fact that thebinder oozes through the tack holes in the inner sole under pressuresuch as at the leveling opera-. tion. The presence of the thermoplasticbinder in the inner face of the innersole is objectionable from manystandpoints. Its presence is readily detected. Its presence oftenresults in discoloration of the stockings of the wearer. This has beenone of the major problems facing the shoe filler to manufacturer. 7

Due to the shortcomings of the thermoplastic fillers, the shoemanufacturers have looked for other types of fillers. Fillers capable ofapplication in the cold have been tried. These fillers {53 usually setup by the evaporation of a solvent and can therefore be applied in thecold state and will set up by exposure to the air or by the action ofmoderate heat and no expensive conditioning equipment is required fortheir use. The cold fillers at present on the market, however, have notovercome the problems which were inherent in the hot fillers and at thesame time certain new problems have come into play.

A. mixture of comminuted soft filling material and dissolved rubber hasbeen used to some extent as a cold filler. This mixture usually isprepared at the shoe factory due to the unstable nature of the binder.There is considerable shinkage upon evaporation of the rubber solventand as a consequence the entire cavity is not filled. The binder doesnot form a tough, tenacious mass and the filler gradually disintegratesupon flexing of the shoe. The material is relatively slow drying andproduction is curtailed while the filler is drying.

It has also been proposed to use a mixture of cork held together with awater solution of gum or other adhesive. This material is relativelyslow-drying and shrinks materially, so that a relatively wide channelexists between the filler and the insole lip upon drying of the filler.This of course is objectionable. The material being water soluble is notextremely waterproof and-takes a relatively long time to set. The gumbinder is somewhat brittleand the filler will crack upon flexing.

More recently a cold filler has been introduced which consists mainly ofmineral fillers held together with a dispersed rubber binder. While thismaterial is fairly satisfactory so far as bond and flexibility areconcerned, the shrinkage is great and the setting progresses slowly.This filler is quite heavy and expensive. It tends to take a permanentset under compression and is not resilient.

In the manufacture of shoes, the innersole is nailed to the last usuallywith five or six nails; three of which commonly are placed in the forepart of the innersole. Prior to the laying of the outsole, the nailswhich hold the innersole to the last are removed and the filler placedin the space formed by the raised lip or channel on the innersole. Theoutsole is subsequently applied. If the outsole is secured by stitchingor nailing, the sole is leveled. This operation consists essentially inapplying high pressure upon the sole by means of rolls which contour theshoe bottom to the desired form. When thermoplastic fillers are used,this pressure forces the binder of the filler through the nail or tackholes in the innersole and causes staining.

In the so-called cemented shoes, the outsole is secured by means of asuitable adhesive. The component parts are first covered with adhesiveand pressed together under considerable pressure. This pressurefrequently forces the binder of the filler through the tack holes in theinnersole as Well as through the thin fiexible outsoles used in womensshoes.

The methods of forming shoes and the problems incident thereto are sowell known in this art that a detailed outline of the various processesand defects is not necessary. I will, however, outline some of thedesired physical characteristics of a bottom filling material:

1. It should be of such character that it can be applied without the aidof heat or other processing at the shoe factory so that a stable productis obtained upon completion of the shoe and expensive processing iseliminated.

2. It should be of an unctuous, slippery nature so that a smooth, evensurface can be quickly and conveniently obtained.

3. It should take a definite set quite rapidly so as to permit furtherprocessing without delay but it should not take a permanent set untilafter the shoe has been finally formed because the sole must becontoured during the leveling operation and the filling must conformgenerally to this shape. The filling should take an initial set in 4 or5 minutes but should not become permanent for at least 10 or 12 hours.

l. It should contain a binder which produces a tough, resilient massupon final setting.

5. It should contain a major portion by volume of a light filler such ascork in order that it will possess a springy, heat insulating characterwhich resists permanent deformation under pressure but which will quitereadily deform under pressure and reexpand to its original shape. a

6. It should contain a'binder which holds the particles together andprevents crumbling or bunching. The binder should preferably berelatively stable at normal temperature so as to maintain its shapeunder warm, moist conditions of usage.

7. It should be flexible after the permanent setting has taken place sothat the filler will not crack upon fiexing of the sole. 7

8. The material should not shrink to any great extent in order that theshoe cavity be entirely filled after setting of the binder.

9. It should contain a binder which firmly and tenaciously secures theindividual filler particles one to the other and forms a homogeneous,tough, flexible, resilient mass. 7

10. It should preferably be waterproof in order to maintain its shapeand characteristics when exposed to moisture. I

I have found that a shoe filler having the desired characteristicsoutlined above can be obtained with the use of an oil-resin gel binderwhich has been modified with a suitable material which toughens thebinder and produces a stable and resilient binding agent.

As a base for the binder of my new shoe filler, I prefer to use asiccative oil-resin gel. Linseed, soya bean, China-wood and menhadenoils are examples of siccative oils suitable for use in my binder. Otherdrying or semi-drying oils or mixtures thereof may be used if desired.

The gel may be produced in any desired manner such for example as byheating or oxidizing. The oil may be mechanically oxidized in thepresence of a resin in the usual heated heaters, such as the Bedfordmachine'or it may be oxidized by the scrim process wherein the oil istrickled over hanging sheets of scrim cloth in a heated chamber until asufiiciently thick layer of gelled oil is obtained. The resin may bethen incorporated with the oil gel so formed by the use of a suitablyheated mixing kettle.

I have found that a thoroughly oxidized oilresin gel produced bymechanically oxidizing a mixture of 90 parts menhaden oil, 10 partslinseed oil and 33 parts rosin forms a satisfactory base for my binder;all parts being given by weight.

This mechanically oxidized oil and rosin is discharged from theoxidizing kettle and allowed to cool. The gel produced is relativelystiff, tough, flexible, and. coherent. The gel is out into piecesconvenient for handling and placed in a suitable mixing machine andsuitable solvents for the gel are added thereto in order to form ajellylike mass which can be readily intermixed with the fillers andwhich will coat the filler particles. For example, with a batch ofgelled oil and rosin weighing about 400 pounds, a mixed solventconsisting of about 245 pounds toluol which is an active solvent for thegel, 245 pounds denatured alcohol which is a substantially inactivesolvent for the gel and 19 pounds turpentine will reduce the stiff gelto a relatively viscous, jellylike mass in about 5 or 6 hours. Theeffect of the above solvents on the oil-rosin gel is to cause the gel toswell by imbibition of the solvent. Only sufficient solvent is used andthe processing time so controlled that the oil-rosin gel is swelled butnot completely dissolved, thus forming the jelly-like mass. If desired,the material may be warmed to about 100 to 110 Bin order to facilitatereduction. The action of the various solvents in the production of myfiller will be more fully described hereinafter.

The toughening agent may consist of nitrocellulose, partially denitratedgun cotton or other cellulose esters. I prefer to use dissolved filmscrap such as sheeted cellulose nitrate or cellulose acetate, which isrelatively cheap and readily available.

Cellulose nitrate film scrap when dissolved forms a very desirabletoughening agent. This may be readily produced by dissolving 17 parts byweight of film scrap in 83 parts by weight of ethyl acetate. I prefer touse just sufiicient solvent to produce a jelly-like viscous mass byswelling. If too much solvent is used there is a tendency for thesolvent to break down the oilresin gel upon mixing the toughening agentwith the binder and the amount of shrinkage of the final product isdependent to some extent upon the amount of solvent used.

The toughening agent may be incorporated into the oil-resin gel base upto about parts by weight of the total batch. The amount of tougheningagent added will depend to some extent upon the hardness desired in thefinal filler and the kind of bulking filler used. I have found that amixture of parts by weight of swollen oilresin binder and 25 parts byweight of toughening agent produces a satisfactory binder for a corkfilling material. Stated in terms of actual binder and tougheningconstituents, less solvents, the mixture would consist of 88.5 parts byweight of oil-resin gel and 11.5 parts by weight of toughening agent.The proportions can be varied to a considerable extent in order to meetthe requirements of the shoe manufacturer.

The oil-resin binder and the toughening agent are thoroughly intermixedto produce a homogeneous mass. 'Ihebinde'r thus formed isthen mixed withthe desired bulking fillers.

A highly satisfactory commercial shoe filler having the desiredcharacteristics above outlined can be produced by mixing a large volumeof cork granules with a minor amount of my binder. For example, aneasily worked filler may be produced by mixing in any suitable mixingmachine a batch consisting of 25 parts by weight of 20 to 30 mesh corkand 150 parts byweight of the toughened binding agent above described.The proportion of cork to binder and solvent is about 3 parts of cork to1 part of binder and solvent by volume or stated in terms of actualbinder and toughening constituents, less solvents, about 8 or 9 parts ofcork to 1 part of binder by volume.

The size of the cork granules can be" varied considerably. A finergranulation of cork will produce a somewhat less resilient fillingmaterial, however. Leather dust, wood flour or other filling materialsmay be used in place of the cork. I prefer to use cork because ofitssoft, springy, resilient nature and also because of its heatinsulating properties. A 'more dense filler will result if mineralfilling material is used.

In the specific example given above, just sufiie oient solvent is usedto produce a viscous oil-resin gel. The gel holds the solventsandpermits more I rapid setting than if there were an excess of solventwhich would be absorbed by the filling material. It is not essentialthat a mixed solvent such as toluol and alcohol be used. Alcohol has alower boiling point than toluol and a more rapidly setting filler isproduced if alcohol is used. A suflicient amount of toluol may be usedas the sovent, however, if a quick setting composition is not essential.In place of toluol, naphtha or solvent naphtha may be substituted and inplace of denatured alcohol, any low-boiling solvent may be used such ascarbon tetrachloride or ethylene dichloride. I prefer to use alcoholbecause of its ,cheapness. In the specific example, 19 parts by weightof turpentine has been used. This serves primarily as a deodorant tokill the odor of the menhaden oil. In place of turpentine any suitabledeodorant may be used, for example, the oil of Wintergreen or Sassafrasor the deodorant may be entirely eliminated if desired.

A swelled oil-resin gel contains a large proportion of solid materialand therefore there is no material shrinkage upon evaporation of thedissolving agents. The swelled oil-resin gel, however, sets up ratherslowly and since a rapid setting material is desired, I prefer to use aquick setting toughening agent in the form of a jelly-like viscous mass.A swelled cellulose ester toughening agent is ideal for this purposesince it produces a tough, tenacious binder and sets up quite rapidlydue to the low-boiling solvent employed. There is, however, a relativelysmall amount of solid matter as compared with volatile matter in thisswelled cellulose ester and for that reason it should be incorporatedinto the oil-resin gel binder in such proportion that shrinking ismaintained at a minimum. In the example given above wherein the ratio ofcork to binder and solvent is 3 to 1 and the ratio of swollen oil-resingel binder to toughening agent is 3 to 1, there is no apparentshrinkage. If the ratio of filler to binder is decreased, the ratio oftoughening agent to oilresin gel should also be decreased if shrinkingis to be kept at a minimum.

I believe there is some interaction between the oil-resin gel and thecellulose ester which actszas a stabilizer of the oil-resin gel. It iswell known that oil-resin gels harden considerably upon aging due tooxidation. I do not limit myself to the theories thus expressed but atany rate, the shoe filler is permanently elastic and flexible.

.In place of ethyl acetate, I may use any lowboiling solvent or mixtureof solvents such as acetone, diacetone alcohol for dissolving thecellulose.

Iumy preferred'embodiment, the rosin, which is added to the oil prior tooxidizing, acts as a Ipeptizer and prevents heat thickening prior tocomplete oxidation. The rosin may be eliminated and a gelled oil will beproduced. The gel will not be thoroughly oxidized, however, and will notpossess the adhesive qualities of an oxidized oil-rosin mixture. Inplace of rosin in my preferred oil gel, I may employ any of the wellknown anti-coagulants possessing adhesive properties, such for exampleas Kauri gum or ester gum which have been used to a considerable extentin the linoleum industry.

When a .mechanically oxidized oil-resin gel is used, the solvents may beadded to the oilresin gel in the oxidizer after the oil-resin gel hascooled sufficiently to prevent any undue volatilization of the solvent.I have successfully introduced the solvents into the oxidizer after themass has cooled to about 170 F. Mixing is continued until the properswelling has taken place.

Oil-resin gels of the type employed in my binder are readily soluble insolvents such as toluol, alcohols, solvent naphtha or combinationsthereof and care must be exercised in the swelling of the oil-resin gelor a thin, nonviscous, relatively liquid material will result uponcontinued mechanical working. By the term readily soluble I mean thatthe oil-resin gel will dissolve by mere intermixing with the solvent orsolvents and does not require autoclaving or other pressure equipment,such as is required to dissolve some oil gels.

The completed filler is usually placed in suitable air-tight cans ordrums for shipment to the shoe manufacturer. The workman simply removesa small portion from the container, (usually sufficient for about twentyminutes work) and places this in a small bowl or container on thework-bench. He then fills the shoes with the aid of a spatula or otherspreading tool. No heating or processing of any sort is required afterthe material reaches the shoe manufacturer.

The material is slippery and is easily applied. It takes a set within afew minutes due to the low boiling solvents. The material upon finalsetting is tough, resilient and does not perma nently deform underpressure. There is little 135 or no shrinkage due to the minor amount ofvolatile constituents compared with the solids. The binder holds thefiller particles tenaciously and prevents crumbling or bunching and atthe same time produces a flexible mass. 140

By the term siccative oil I wish to include both drying and semi-dryingoils.

While I have described certain specific preferred embodiments of myinvention, it will be understood that the invention is not limited to14% the specific examples but may be otherwise embodied and practicedwithin the scope of the following claims.

I claim:

l. A cold spreadable shoe filler composition 150 consisting of a mixtureof comminuted resilient substantially non-absorbent filler, a swelledsiccative oil-resin gel binder, and sufficient quick drying solution ofa cellulose ester toughening agent to impart a rapid initial set butinsuffie cient tovimpart noticeable shrinkage, made in accordance withthe method of claim.5.

2. A cold spreadable shoe filler composition comprising a major portionby volume of a comminuted filler and a viscous jelly-like binderincluding a homogeneous mixture of asiccative oil-resin gel swelled byimbibition of an organic solvent in which said oil-resin gel is readilysoluble, a minor amount of cellulose ester, and suliicient low-boilingsolvent to swell the cellulose ester to a jelly-like consistency, saidbinder coating said comminuted filler without impregnation.

3. A cold spreadable shoe filler composition comprising a major portionby volume of comminuted cork and a viscous jelly-like binder including ahomogeneous mixture of a siccative oil-resin gel swelled by imbibitionof an organic solvent in which said oil-resin gel is readily soluble anda quick setting solvent swelled cellulose ester toughening agent of ajelly-like consistency, the quantity of said swelled siccative oilrosingel exceeding the quantity of toughening agent and inhibiting shrinkageduring the setting of the composition.

a. A cold spreadable shoe filler composition comprising a majorportionby volume of a comminuted filler and a viscous jelly-like binder coatingsaid filler and including a mixture of siccative oil-resin gel swelledby imbibition of an organic solvent in which said oil-resin gel isreadily soluble and a quick setting cellulose ester toughening agent inthe form of a viscous gel, the ratio of filler to binder beingsubstantially the same as the ratio of swelled siccative oil-resin gelto cellulose ester gel.

5. In the method of making a cold spreadable shoe filler composition,the steps consisting in forming a siccative oil-resin gel, swelling saidgel by imbibition of solvent to form a jelly-like mass, forming acellulose ester gel, mixing the gels to form a homogeneous viscousjelly-like mixture and adding a comminuted filler material to said gelmixture.

6. In the method of making a cold spreadable shoe filler composition,the steps consisting in forming a stiii oxidized gel of a siccativeoilrosin mixture, swelling said gel by imbibition of a solvent until ajelly-like mass is obtained, forming a cellulose ester toughening agentby soaking said cellulose ester in sufficient low-boiling solvent toform a swelled gel of a jelly-like consistency, mixing the gels to forma viscous mixture and adding comminuted cork to said mixture.

7. In the method of making a cold spreadable shoe filler composition,the steps consisting in forming a siccative oil-adhesive resin gel,swelling said gel by imbibition of a mixture of active and inactiveorganic solvents to form a jelly-like mass, forming a cellulose estergel, mixing substantially three parts of said oil gel with one part ofsaid cellulose ester gel to form a homogeneous viscous jelly-likemixture and adding substantially three parts by volume of commnuted corkto one part by volume of said mixture and mixing the mass to form atenacious, resilient filling material possessing a rapid initial set anda delayed permanent set.

8. A cold spreadable shoe filler composition comprising a major portionby volume of comminuted cork as a base and a binder for said baseincluding a jelly-like mixture of a siccative oilresin gel swelled byimbibition of an organic solvent in which said oil-resin gel is readilysoluble and a cellulose nitrate toughening agent of jelly-likeconsistency.

9. A cold spreadable shoe filler composition comprising a mixture ofcomminuted cork and a binder in the form of a jelly-like mixture andincluding an oxidized siccative oil-resin gel swelled by imbibition of arelatively high boiling organic solvent in which said oil-resin gel isreadily soluble and a cellulose ester toughening agent swelled in arelatively low boiling solvent, said filler being soft, flexible andwaterproof, will set up rapidly without substantial shrinkage and may becontoured subsequently to the initial set.

RICHARD ALMY.

